Catalytic combustion surfaces and method for creating catalytic combustion surfaces

ABSTRACT

A coating and coating process to improve the efficiency of hydrocarbon fueled engines, wherein the coating includes a high percentage of nickel to create a reaction which improves the combustion efficiency of the hydrocarbon fuel. The coating may also include chromium, iron, and other constituents and is applied to combustion surfaces with a sufficient bonding strength to allow the coating to function in the combustion chamber, while providing a surface having sufficient surface roughness to promote the chemical reaction underlying the combustion efficiency improvement. The nickel causes a catalytic cracking reaction to ease the combustibility of hydrocarbon molecules in the fuel.

This application is a continuation of U.S. patent application Ser. No.09/920,132, filed Aug. 1, 2001 and entitled “CATALYTIC COMBUSTIONSURFACES AND METHOD FOR CREATING CATALYTIC COMBUSTION SURFACES, theentire disclosure of which is hereby incorporated by reference herein asif being set forth in its entirtey.

The present invention relates generally to increasing the efficiency andreducing emissions of internal combustion in engines. More particularly,the present invention relates generally to the application of coatingsto internal combustion engines for the purpose of reducing unwantedemissions, and more particularly to the application of nickel coatedmaterials to the combustion surfaces of reciprocating piston internalcombustion engines to promote fuel combustion efficiency.

BACKGROUND

Internal combustion engines using hydrocarbon fuels are widely used dueto their ability to create mechanical energy from a fuel that providespower for a sufficient time period without requiring complex or largefuel storage associated with the engine. Internal combustion engines mayutilize the Diesel cycle, wherein self-ignition of the hydrocarbon fuelis used to initiate combustion of the hydrocarbon fuel. Hydrocarbon fuelused in Diesel cycle engines typically contains heavier petroleumfractions than the hydrocarbon fuel used in engines having sparkignition systems. The fuel having the heavier hydrocarbon fractions istypically called diesel fuel, even though the fuel can be used in sparkignited and spark assisted ignition engines designed to combust theheavier fractions. Engines using diesel fuel are widely used incommercial vehicles due to inherent efficiencies associated with thediesel fuel and the diesel cycle. Fuels utilizing the heavierhydrocarbon fractions tend to be less expensive than fuels using lighterhydrocarbon fractions, due to lower demand and reduced refining costs.The use of the higher fractionated fuel allows diesel fueled engines toutilize a higher compression ratio, resulting in a higher combustionefficiency.

Although diesel fueled engines are preferred in commercial applications,the use of diesel fueled engines is not without room for improvement.Normal operation of diesel fueled engines results in the production ofharmful emissions, including soot and unburned hydrocarbon molecules.Diesel fueled engines tend to have higher exhaust emissions,particularly soot, when heavily loaded, or run in an improper state oftuning. Also, the cost of operating a diesel fueled engine is heavilyinfluenced by the cost of the fuel being used in the engine.

The use of catalytic materials in the exhaust stream of hydrocarbonfueled engines has been implemented to reduce unwanted emissions. Thecatalytic effect in the exhaust stream accomplishes a reduction ofunwanted emissions, but accomplishes the reduction of the unburnedhydrocarbons downstream from the combustion chamber, such that energyreleased through the catalytic reaction is not utilized, and must berejected as waste heat. Thus, the catalytic reaction provides noefficiency in the conversion of the hydrocarbon fuel into mechanicalenergy.

Technologies such as low heat rejection (LHR) coatings are beingdeveloped to improve the efficiency of fuel combustion in diesel fueledengines. LHR engines rely on the use of combustion surface coatingswhich form insulation or thermal barriers, thus retaining the heat ofcombustion within the combustion volume, allowing more of the combustionenergy to be converted into mechanical energy, thus reducing the fuelconsumption for a given power level. LHR technologies are presentlydirected towards the use of ceramic coatings applied to the combustionsurfaces of an engine to inhibit heat transfer from the combustionproducts to the engine block and heads. The use of ceramic materials,however, raises issues related to lubrication of the reciprocatingcomponents, as well as to the formation of deposits on the coatingsurfaces (referred to as “coking”) which inhibit combustion efficiency.

U.S. Pat. No. 5,987,882 to Voss et al. is directed towards combining aceramic layer with an oxidation catalyst material, such as a rare-earthmetal oxide. The described multi-component coating is claimed toincrease the efficiency of combustion by retaining heat within thevolume where the coating is applied. A benefit associated with suchretention is an improved performance of the catalyst material, due toincreased chemical action of the catalyst at elevated temperatures.Application of the coating to combustion surfaces of a reciprocatingengine is described in the patent. The application described requiresthe integration of a bond coat as a bonding substrate below theinsulative coating. The bond coat used for the described examplesconsisted of a 4 mil metal-aluminum-chromium-yttrium alloy, preferablyusing nickel, cobalt, or iron for the metallic component.

The use of rare-earth metallic oxide catalytic materials is, may be,however, susceptible to poisoning of the catalyst material. Sulfurcontained in fuel to which the catalyst material is exposed preventscatalysts from functioning properly by causing sulfate production thatinhibits catalyst regeneration. Accordingly, the use of catalytictechnologies which incorporate materials such as platinum andpraeseodymium oxide may be problematic when used with current dieselfuel, which contain sulfur levels sufficient to cause poisoning of thecatalyst materials.

Other efforts towards improving the combustion efficiency of dieselfueled engines have been directed towards improved fuel formulations,combustion chamber size and shape, and the use of pre-ignition chambers.Each of these technologies may provide some gain with respect tocombustion efficiency, however the costs associated with theirimplementation are not optimal when considered in light of thecommercial applications in which the diesel fueled engines are used. Theexpense of reformulated fuels directly increases the operating costs ofengine utilization. Intricate combustion chamber shapes, pre-ignitionchambers, and ceramic-metallic coatings add to the production cost andcomplexity of the engines, as well as complicate maintenance issues andpotentially the reliability of the engines themselves.

The use of coatings on engine components, including diesel fueled enginecomponents, has generally been directed towards reduction of frictionbetween components of the engine. The principal areas of interest havebeen the walls of the cylinder bore and the sealing rings, which extendbetween the skirt of a piston and the cylinder bore. U.S. Pat. No.5,866,518 to Dellacorte et al. describes a composite material for use inhigh temperature applications. The Dellacorte composite consistsprimarily of chromium dioxide (60-80% by weight) in a metal binderhaving at least 50% nickel, chromium, or a combination of nickel andchromium. The greatest proportion of binder described is 60%, such thatthe highest proportion of nickel used in the coating is 30%, at whichpoint no chromium is included. The Dellacorte patent describes thecomposite as providing a self-lubricating, friction and wear reducingmaterial to be applied to the sealing rings.

U.S. Pat. No. 5,292,382 to Longo describes a sprayable molybdenum/ironcoating which may be sprayed on piston rings as a means of reducingfriction. The composition of the Longo material is described as 25-40%molybdenum, 4-8% chromium, 12-18% nickel, and 25-50% iron, with carbon,boron, and silicon additionally included in the composition.

SUMMARY OF THE INVENTION

The present invention is directed towards a combustion chamber surfacecoating and method for applying the coating to improve the combustionefficiency of internal combustion engines, particularly, but notnecessarily limited to, those utilizing diesel fuel. The coatingimproves the combustion efficiency through a catalytic reaction with thehydrocarbon based fuel which causes hydrocarbon molecules todisassociate into free radicals at an accelerated rate. The higherconcentration of free radicals drives the combustion reaction to afaster and more complete combustion of the hydrocarbon fuel, thusobtaining energy from the fuel more efficiently, as the more completecombustion provides more power per unit of fuel and less unwantedemissions.

The catalytic reaction is accomplished by providing a nickel surface oncomponents which form the combustion chamber of the engine. The nickelreacts with the hydrocarbon molecules in a catalytic reaction whichproduces the free radicals. Although the nickel is believed to be thecomponent driving the reaction, the use of a pure nickel surface may belimited only by the inactive characteristics of nickel in providing asurface with sufficient structural characteristics to provide a durableand reliable surface. Accordingly, the nickel may be alloyed with othermaterials to provide sufficient durability and reliability when used inthe combustion chamber environment. Presently, an alloy comprisingnickel, chromium, and iron has been employed, however other materialsmay be substituted, interchanged, or included in the composition asindicated by desired other properties.

The amount of free radicals which can be dissociated from hydrocarbonmolecules is generally understood to be dependant on the contact of thehydrocarbon molecules and the nickel, and thus the amount of exposedsurface area of the nickel appears to be related to the improvements incombustion efficiency gained. In addition to increasing the coatingarea, the surface of a coated area may be increased by forming thecoating with a less smooth surface. Accordingly, the nickel surface maybe formed by applying a coating according to the present invention tosurfaces which form the combustion chamber by a high velocity oxygenflame process. This deposition method typically results in a coatinghaving sufficient bonding strength to underlying structure to providesufficient durability, while providing a surface roughness which limitscoking of the engine while providing increased contact area between thenickel and hydrocarbon molecules.

In a first form, the present invention may be embodied in an internalcombustion engine having at least one reciprocating component, a borewithin which the at least one reciprocating component reciprocates, anda closure over one end of the bore. The reciprocating component has acombustion face. The reciprocating component reciprocates relative tothe closure between TDC and BDC positions. A combustion volume isdefined at least in part by the combustion face of the reciprocatingcomponent, and a surface of the closure. At least a portion of thesurfaces which define the combustion volume are coated with a metalliccoating which includes nickel, such that when the combustion face is atthe position at which the combustion face is at a closest point to theclosure, it has been noted that it is preferable to have at least 10% ofthe surfaces which define the combustion volume are coated with thecoating, although lesser amounts of coating may also have efficiency.

In an alternate form, the present invention may be embodied in aninternal combustion engine having a combustion volume and areciprocating piston, with the reciprocating piston having a combustionface and the combustion engine further having a combustion volume. Thecombustion volume may be bounded by combustion surfaces. The combustionsurfaces may include the combustion face of the reciprocating piston. Aportion of the combustion surfaces equivalent in area to one tenth ormore of the combustion face area is coated with a composition that isexposed to combustion gases. In its form, the composition may includebetween approximately 2% and approximately 80% nickel, betweenapproximately 10% and approximately 30% chromium, and betweenapproximately 10% and 90% iron, although other compositions may bepossible.

In a further form, the present invention may be embodied in a processfor reducing particulate emissions in a diesel fuel powered internalcombustion engine, wherein the internal combustion engine comprises atleast one cylinder having a combustion chamber. The process includes thesteps of coating at least a portion of the inner surfaces of thecombustion chamber with a composition which may include between 2% and80% nickel and 10% and 40% chromium, (although other compositions may bepossible) where the coating forms a surface exposed to combustion gases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an illustration of an internal combustion engine to which thecoating of the present invention has been applied, illustrating thecombustion surfaces associated with the coating of the presentinvention.

FIG. 1B is an illustration of an internal combustion engine to which thecoating of the present invention has been applied, illustrating thepiston in the top-dead-center (hereafter “TDC”) position.

FIG. 1C is an illustration of an internal combustion engine to which thecoating of the present invention has been applied, illustrating thepiston in the bottom-dead-center (hereafter “BDC”) position.

FIG. 2 is an illustration of the head of a Yanmar TS180C research engineused in the first illustrative embodiment, to which the coating of thepresent invention has been applied, identifying characteristicsassociated with the engine.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, wherein like reference numerals indicate likeelements, there is shown the components of a diesel engine 100 to whichthe coatings of the present invention have been applied.

As shown in FIG. 1, a simple Diesel cycle reciprocating piston internalcombustion engine includes a piston 102 that reciprocates in a bore 104.The bore 104 is closed at one end. The reciprocating piston 102reciprocates between two positions. One position, commonly referred toas top dead center (shown in FIG. 1B and hereafter referred to as “TDC”106), occurs when the piston is at its closest point of travel to theclosed end of the bore. The other position, commonly referred to asbottom dead center (shown in FIG. 1C and hereafter referred to as “BDC”108), occurs when the piston 102 is at its farthest point of travel fromthe closed end of the bore 104. Typically, the walls of the bore 104 maybe integrally formed in an aluminum or cast iron engine block 110, ormay be formed by liners inserted into an engine block 110. The walls ofthe bore 104, in conjunction with the closure at the one end of the bore104 and the combustion face 112 of the piston 102, form the boundary ofthe combustion volume 114 associated with the piston 102. Owing to themotion of the reciprocating piston 102, the volume of the combustionvolume 114 is not fixed, but rather varies with the position of thepiston 102 within the bore 104.

In a typical engine, such as a diesel engine 100 to which the presentinvention may be applied, the closed end of the bore is formed by a head116 that is bolted over one end of the bore 104. The head 116 istypically formed from cast iron. The head 116 typically includes apocket 118 formed into the head 116 to provide a shaped pocket toimprove the flow of an air/fuel mixture into and out of the combustionvolume 114, which is typically accomplished through intake 120 andexhaust valves 122. The pocket 118 in the head 116 is typically calledthe combustion chamber, although the pocket 118 does not provide all ofthe surfaces that define the volume 114 within which combustion occurs.The intake 120 and exhaust 122 valves are typically located in the head116 for manufacturing and maintenance concerns. When the valves 120,122, are located in the head 116, the face of the intake valve 124 andthe face of the exhaust valve 126 may form portions of the surfaces thatform the combustion volume 114.

Accordingly, the surfaces to which the air/fuel mixture is exposed whilethe engine 100 is operating, thus bounding the combustion volume, mayinclude, but are not limited to, the portion of the head and valveswhich close the bore 104, the side walls of the bore dependant on theposition of the piston 102, and the combustion face 112 of the piston.Additionally, the use of sealing rings 128 between the piston 102 andthe bore 104 may result in a surface of a sealing ring 128 forming aportion of the surface which bounds the combustion volume 114.

Application of the nickel coating of the present invention to thesesurfaces causes exposure of hydrocarbon molecules to the nickel thatforms a portion of the coating. It is believed that the hydrocarbonmolecules transform in the presence of the nickel, resulting in a freeradical of a hydrocarbon molecule being chemisorbed to the nickel. Attemperatures generally above approximately 700 degrees Fahrenheit, thefree radical may be dissociated from the nickel coating. Such a freeradical may combine more easily with oxygen during the combustionprocess, resulting in improved combustion efficiency.

Diesel fuels may be categorized by their cetane number. Cetane is C₁₆H₃₄and contains methyl groups that are attached in a manner such that nofree radicals are present. The cetane number is the percentage by volumeof cetane in a mixture of liquid methylnaphthalene that gives the sameignition lag as the oil being tested.

When cetane or similar molecules are chemisorbed by metallic nickel,sufficient activation energy is imparted to the cetane molecule (orother hydrocarbon molecules) such that free methyl radicals may beformed. These free radicals may initiate chain reactions in hydrocarbonmolecules away from the surface of the metallic nickel. In this mannermolecules break up due the catalytic effect to the point where a fasterand more complete combustion takes place.

The motion of gaseous molecules comprising the combustion gases is alsobelieved to create friction between the molecules that generates bothlight and ions to form a corona. The effect of exposed dissimilar metalsassociated with a partially coated combustion volume is believed topromote the formation of this corona. This corona is believed to bedischarged during the intake/combustion cycle, and energy associatedwith the discharge is believed to further oxidize hydrocarbons, residualcarbon monoxide action and nitric oxide.

The corona effect is discussed in U.S. Pat. No. 6,047,543 to Caren etal. This patent discusses the use of a 25-watt device for generating acorona that is installed between the engine and a catalytic converter,.It is believed that hydrocarbons, residual carbon monoxide and nitricoxide may be oxidized by ionized oxygen in the presence of freeelectrons which results from the corona generating device.

The effect of magnetizing a surface to be coated during the coatingprocess, as discussed further below, is believed to further strengthenthe corona effect through the formation of additional ions. Thismagnetic effect is recognized in the waste water treatment systems,available commercially, where magnets are used to induce ionization andsubsequent aqueous oxidation of hydrocarbons to water and carbondioxide.

Although nickel is the element with which the hydrocarbon moleculesreact, the coating must have sufficient strength to withstand thepressures and effects of the combustion of the air fuel mixture (notshown). These effects include rapidly cycling temperatures, erosiveeffects associated with the flow of the air/fuel mixture into thecombustion chamber, erosive effects associated with the flow ofcombusted air/fuel mixture out of the chamber, and corrosive effectsassociated with the combustion products in the high temperatureenvironment resultant from combustion.

Accordingly, the use of a pure nickel coating is not advantageous, inthat the nickel does not possess adequate strength to provide thesurface unless alloyed with other materials. The addition of chromiumand iron has been shown to provide adequate coating properties toprovide adequate durability when used in commercial applications. Asiron has catalytic properties of its own, the use of iron in thecomposition both provides needed structural properties, as well as mayadditionally improve the catalytic effect of the coating. The additionof chromium provides anti-corrosion properties which are beneficial tothe durability of the coating. Other metals having catalytic properties,such as, but not limited to, cobalt, rhodium, osmium and iridium mayalso be incorporated.

The material selected must be chosen with consideration of the abilityto withstand the thermal and pressure cycling associated with thecombustion conditions within the combustion chamber. It is presentlybelieved that ferritic stainless steels provide advantageous mechanicalproperties due to their lower tendency to become brittle in response tothermal cycling.

Commercially available alloys may be used for the coating material, suchas 17-4 stainless steel or Inconel 625. The use of commerciallyavailable alloys may allow reductions in the cost of preparing thecoating due to the off-the-shelf nature of the alloy, as opposed to thecosts associated with having custom alloys prepared by a supplier.Inconel 625 contains a significant amount of molybdenum (approximatelyabout 8-10%) to reduce friction between components in the reciprocatingengine. When applied, however, to surfaces such as the combustion face112 of the piston 102 and the pocket 118 formed in the head 116, thefriction reduction properties are unnecessary, since there is no slidingcontact between these components and any other component of the engine.Inconel has the further advantage of having a high Nickel content(approximately about >%58) to promote the catalytic interaction betweenthe coating and combustion gases.

Earlier disclosures, such as Longo described above, teach the use ofcoatings comprising nickel and molybdenum to provide adequate surfacecharacteristics for sealing rings for reciprocating piston internalcombustion engines, however the small surfaces of the rings 128 exposedto the combustion chamber are inadequate to provide a significant effectassociated with coating larger portions of the combustion surfaces.Additionally, the positioning of the sealing rings 128 typically resultsin the exposed surface of the top sealing ring 130 being shrouded fromthe air/fuel mixture by the piston 102.

As the efficiency improvement resultant from the present coating isresultant from interaction between hydrocarbon molecules and the nickelcontained in the coating, it may be advantageous to select a surfacefinish to maximize the surface area of the coating exposed to thehydrocarbon molecules without forming an overly rough surface. Overlyrough surface coatings promote coking of the combustion surfaces, whichprevents exposure of the nickel content to the hydrocarbon molecules.

The coating may be applied to combustion surfaces using high velocityoxygen flame spray methods. Other known application methods may also beemployed. These methods result in a surface roughness of approximately200 RMS surface finish, as compared to a surface roughness ofapproximately 300 RMS associated with normally machined surfaces used incombustion engines. However, any suitable surface roughness may beemployed to achieve the desired combustion characteristics.

The selection of surfaces on which to apply the coating may be madebased on the cost of applying the coating to the component, the amountof exposed surface area that can be obtained through coating thecomponent, and the utility of the coating on the surface to which thecoating is to be applied. Coating friction surfaces such as sealingrings 128 and the bore 104 or bores of the engine may not be beneficial,due to the surface smoothness requirements of these components. The borewalls are not continuously exposed to the combustion products, as thetravel of the reciprocating piston 102 alternately exposes and shieldsthe walls from the combustion volume 114. The action of sealing rings128 sliding across the walls also requires the presence of a lubricantto reduce friction between the components. The presence of the lubricantinhibits the reaction between hydrocarbon fuel molecules and the nickelby being interposed between the nickel surface and the hydrocarbon fuel.Accordingly, coated surface selection must be made in light of thebeneficial effect that can be obtained by providing the coating.

The surfaces that provide the greatest benefit from coating are thesurface of the pocket 118, the combustion face 112 of the piston 102,and the intake 124 and exhaust 126 valve faces. If the coating is beingapplied to a disassembled engine, access constraints are minimal. Ifonly the head 116 of the engine is disassembled, such as during amaintenance action, the coating can be applied to the interior face ofthe combustion chamber and/or valve faces. Application of a coating tocombustion face 112 of the piston may be problematic where the piston102 remains in the bore 104 of the engine 100, such that an intermediatebenefit can be obtained by coating only the interior face of the pocket118, the faces of the intake 126 and/or exhaust 128, or a combination ofthese surfaces.

Alternatively, the use of the coating can be extended upstream ordownstream from the combustion chamber. Since it is believed that thecatalytic effect of the material is a cracking effect as opposed to anoxidation effect, the application of the catalytic material upstreamfrom combustion chamber may allow greater reduction of heavier fractionsprior to combustion. This effect will be limited where direct injectionis utilized, due to the lack of fuel hydrocarbon, in the intake stream.Additionally, the cracking effect may also reduce unwanted emissions byreducing heavier hydrocarbon fractions in the exhaust stream.

FIRST ILLUSTRATIVE EMBODIMENT

A six-cylinder diesel engine installed in a Ford 7000 cargo truck wasused as a proof of concept test project. The engine was originally madein Brazil, and had been used commercially for approximately 160,000miles before being procured for the present testing.

The characteristics of the engine are listed in Table 1 below.

The 6.6 L engine includes 6 cylinders in an in-line configuration. Theengine utilizes a cast iron block and head. The engine does not utilizeliners in the bores. The head contains 6 intake and 6 exhaust valves,one of each per cylinder. TABLE 1 No of Cylinders:   6 EngineDisplacement:   6.6 L Engine Bore:  111.8 mm Engine Stroke:  111.8 mmPiston Diameter: 111.34 mm Intake Valve Diameter:  47.99 mm ExhaustValve Diameter:  42.74 mm Compression Ratio: 17.5:1 Surface Area ofPiston (SA_(p)) (based on   9736 mm Piston Diameter): Surface Area ofCombustion Chamber: 6573 (Estimate) Surface Area of Valves: 3243.4Coated Surface Area (SAC): 9816 Ratio SAC to SA_(p):   1.008

An initial emissions test in accordance with the New Jersey Methodologyyielded an opacity rating of 25.6. The engine was cleaned usingMotorVac™ equipment. The MotorVac™ equipment uses a diesel fuelfortified with cleaning agents to remove deposits from the fuel systemsand combustion chamber of the diesel engine. An engine being cleanedusing the MotorVac™ is operated with the substitute fuel to cause thefortified diesel fuel to be circulated through the engine.

Following completion of the cleaning process, the engine was emissionstested utilizing the original uncoated cast iron head. In accordancewith the New Jersey opacity test, the engine yielded an opacity ratingof 19.8. The cast iron head was then coated in accordance with thepresent process with a 4-5 mil thick coating of no more than 0.07%carbon, between 15 and 17% chromium, 4% nickel, 2.75% copper, and 75%iron and trace elements (this composition is commonly called “17-4Stainless Steel”). The engine was then again tested in accordance withthe New Jersey opacity testing standard, and yielded an opacity ratingof 17.6.

As a means of correlating the amount of coated area within thecombustion chamber to the total combustion chamber surface area, thecoated area of a single combustion chamber may be expressed as a ratioof the coated area to the area of the combustion face of the piston,hereafter called the coating factor. Using such a measurement allows theratio to be expressed without requiring definition of a fixed combustionchamber area, since the combustion ratio surface varies as the pistonreciprocates.

For the engine of the present illustration, the diameter of the bore is111.8 mm. Due to the necessity of under sizing the piston relative tothe bore, the piston has a minimum allowable diameter of 111.34 mm.Accordingly, the area of the combustion face is approximately 9736 mm²(assuming a flat top piston). If the combustion face of a 47.99 mmintake valve were coated, the surface area of the coating would beapproximately 1808 mm², yielding a coating factor of approximately0.185. If both the combustion face 126 of the piston 102 and the face124 of the intake valve 120 were coated, the coating factor would beapproximately 1.185. It is evident from this that the coating factor canexceed unity, since the total area bounding the combustion includes thearea of the combustion face as well as the area of the pocket 118, valvefaces 120, 128, and exposed portions of the bore 102.

In the sample engine embodiment, the interior surface of the combustionchamber and the faces of the valves were coated. The combustion face ofthe piston, and the walls of the bore remained uncoated. It is estimatedthat the surface area of the coated portion of the combustion chamberwas approximately 9816 mm², yielding a coating factor of approximately1.008. As noted above, this engine was run in both uncoated and coatedconditions. The operating efficiency of the engine as indicated byemissions from the engine were as shown in Table 2. TABLE 2Configuration Description Opacity Baseline 26.8 After MotorVac 19.8Coated (after MotorVac) 17.6

The application of the coating was not limited to the interior surfaceof the combustion chamber, but rather extended onto the mating surfaceof the head where the head mates to the engine block. It is important tonote that the mating surface of the head was milled prior to coating toremove an equivalent thickness to the coating thickness to mitigate anyeffects that could have been caused by increased combustion volumeresultant from the additional thickness of the coating on the matingsurface.

SECOND ILLUSTRATIVE EMBODIMENT

The coating of the present invention has also been applied to a singlecylinder Yanmor TS180C research engine. The research engine uses atypical cross flow head, as shown in FIG. 4. The engine also utilizesdirect injection. The parameters of the engine were as follows: TABLE 3Engine Displacement:   8661 L Engine Bore:   102 mm Engine Stroke:   106mm Piston Diameter:   101 mm (estimate) Intake Valve Diameter:  42.7 mmExhaust Valve  33.5 mm Diameter: Compression Ratio: 19.8 Surface Area ofPiston 8011.6 mm² (SAp) (based on est. Piston Diameter): Surface Area of  5890 mm² (est.) Combustion Chamber: Surface Area of 2313.4 mm² Valves:Coated Surface Area   8200 mm² (est.) (SAC): Ratio SAC to SAp:  1.023

The performance improvements resultant from coating the head and valves(which yielded a 1.023 SAC to SA_(p) ratio) were as shown in thefollowing table. The mode 4 data appears to yield aberrant data, howeverthis is believed due to effects associated with the slow speed inconjunction with the single cylinder configuration. As averaged betweenthe various modes, the resultant improvements were as follows: TABLE 4Constituent Baseline Coated Head % Change HC 1.101877 g/kW-hr .855357g/kW-hr −22.4% CO 3.66792 g/kW-hr 3.66792 g/kW-hr −22.1% CO₂ 908.0019g/kW-hr 983.3241 g/kW-hr +8.3% NO 5.867477 g/kW-hr 8.17224 g/kW-hr+39.3% NO₂ 0.853066 g/kW-hr .543094 g/kW-hr −36.3% Particulate 1.937068g/kW-hr 1.392242 g/kW-hr −28.1% (PM)

Baseline mair/mfuel 14.673652 Mode IV MAF (freq) 3143 Hz Air Fuel Ratio95.1 HC 0.0373 g/min Brake Power 1.50 kW Mass Air Flow 803 g/min ExhaustDensity 0.843 kg/m3 CO 0.180 g/min HC 1.49 g/kW-hr Fuel Consumption 8.44g/min Mass Exhaust 811 g/min CO₂ 26.9 g/min CO 7.22 g/kW-hr ExhaustTemp. 154° C. Volume Exhaust 0.962 m3/min NO 0.216 g/min CO₂ 1076g/kW-hr HC 92.5 ppm Moles in Exhaust 27.5 mol/min NO₂ 0.0372 g/min NO8.65 g/kW-hr CO 235 ppm HC 0.00254 mol/min HC 4.41 g/kg fuel NO₂ 1.49g/kW-hr CO₂ 31375 ppm CO 0.00644 mol/min CO 21.4 g/kg fuel Fuel 338g/kW-hr Consumption NO 262 ppm CO₂ 0.611 mol/min CO₂ 3184 g/kg fuelParticulate 5.04 g/kg fuel NO₂ 29.5 ppm NO 0.00720 mol/min NO 25.6 g/kgfuel Particulate 1.70 g/kW-hr speed 1380 rpm NO₂ 0.000809 mol/min NO₂4.41 g/kg fuel load 7.65 fl-lb Theoretical CO₂ 22243 → % Difference 41.1particulate mass 2.86 mg Mode III MAF (freq) 3479 Hz Air Fuel Ratio 59.3HC 0.0995 g/min Brake Power 3.83 kW Mass Air Flow 1095 g/min ExhaustDensity 0.704 kg/m3 CO 0.214 g/min HC 1.56 g/kW-hr Fuel Consumption 18.5g/min Mass Exhaust 1114 g/min CO₂ 59.5 g/min CO 3.34 g/kW-hr ExhaustTemp. 238° C. Volume Exhaust 1.58 m3/min NO 0.387 g/min CO₂ 931 g/kW-hrHC 180 ppm Moles in Exhaust 37.7 mol/min NO₂ 0.0671 g/min NO 6.05g/kw-hr CO 202 ppm HC 0.00679 mol/min HC 5.39 g/kg fuel NO₂ 1.05 g/kW-hrCO₂ 49690 ppm CO 0.00763 mol/min CO 11.6 g/kg fuel Fuel 289 g/kW-hrConsumption NO 342 ppm CO₂ 1.35 mol/min CO₂ 3225 g/kg fuel Particulate9.88 g/kg fuel NO₂ 38.7 ppm NO 0.0129 mol/min NO 20.9 g/kg fuelParticulate 2.85 g/kW-hr speed 1773 rpm NO₂ 0.00146 mol/min NO₂ 3.63g/kg fuel load 15.2 ft-lb Theoretical CO₂ 35874 → % Difference 38.5particulate mass 8.93 mg 13.23 Mode II MAF (freq) 3703 Hz Air Fuel Ratio44.8 HC 0.112 g/min Brake Power 6.63 kW Mass Air Flow 1313 g/min ExhaustDensity 0.588 k/m3 CO 0.311 g/min HC 1.01 g/kW-hr Fuel Consumption 29.3g/min Mass Exhaust 1342 g/min CO₂ 96 g/min CO 2.82 g/kW-hr Exhaust Temp.340° C. Volume Exhaust 2.284 m3/min NO 0.580 g/min CO₂ 865 g/kW-hr HC167 ppm Moles in Exhaust 45.4 mol/min NO₂ 0.0823 g/min NO 5.25 g/kW-hrCO 245 ppm HC 0.00760 mol/min HC 3.80 g/kg fuel NO₂ 0.745 g/kW-hr CO₂68148 ppm CO 0.0111 mol/min CO 10.6 g/kg fuel Fuel 265 g/kW-hrConsumption NO 426 ppm CO₂ 2.17 mol/min CO₂ 3260 g/kg fuel Particulate7.13 g/kg fuel NO₂ 39.4 ppm NO 0.0193 mol/min NO 19.8 g/kg fuelParticulate 1.89 g/kW-hr speed 2007 rpm NO₂ 0.00179 mol/min NO₂ 2.81g/kg fuel load 23.3 ft-lb Theoretical CO₂ 47824 → % Difference 42.5particulate mass 8.50 mg Mode I MAF (freq) 3811 Hz Air Fuel Ratio 35.8HC 0.105 g/min Brake Power 9.01 kW Mass Air Flow 1424 g/min ExhaustDensity 0.495 kg/m3 CO 0.506 g/min HC 0.700 g/kW-hr Fuel Consumption39.7 g/min Mass Exhaust 1463 g/min CO₂ 131 g/min CO 3.37 g/kW-hr ExhaustTemp. 454° C. Volume Exhaust 2.96 m3/min NO 0.779 g/min CO₂ 871 g/kW-hrHC 145 ppm Moles in Exhaust 49.5 mol/min NO₂ 0.0750 g/min NO 5.19g/kW-hr CO 365 ppm HC 0.00717 mol/min HC 2.65 g/kg fuel NO₂ 0.499g/kW-hr CO₂ 87506 ppm CO 0.0181 mol/min CO 12.8 g/kg fuel Fuel 264g/kW-hr Consumption NO 524 ppm CO₂ 2.98 mol/min CO₂ 3296 g/kg fuelParticulate 5.82 g/kg fuel NO₂ 32.9 ppm NO 0.0260 mol/min NO 19.6 g/kgfuel Particulate 1.54 g/kW-hr speed 2199 rpm NO₂ 0.00163 mol/min NO₂1.89 g/kg fuel load 28.9 ft-lb Theoretical CO₂ 60060 → % Difference 45.7particulate mass 8.61 mg ISO 8178 Weighted Average Totals HC 1.101877g/kWh CO 3.66792 g/kWh CO₂ 908.0019 g/kWh NO 5.867477 g/kWh NO₂ 0.853066g/kWh Particulate 1.937068 g/kWh

Coated Head Mode IV MAF (freq) 3191 Hz Air Fuel Ratio 89.4 HC 0.0448g/min Brake Power 1.45 kW Mass Air Flow 842 g/min Exhaust Density 0.817kg/m3 CO 0.146 g/min HC 1.85 g/kW-hr Fuel Consumption 9.41 g/min MassExhaust 851 g/min CO₂ 30.0 g/min CO 6.05 g/kW-hr Exhaust Temp. 168° C.Volume Exhaust 1.04 m3/min NO 0.338 g/min CO₂ 1240 g/kW-hr HC 106 ppmMoles in Exhaust 28.8 mol/min NO₂ 0.0264 g/min NO 14.0 g/kW-hr CO 181ppm HC 0.00305 mol/min HC 4.76 g/kg fuel NO₂ 1.09 g/kW-hr CO₂ 49438 ppmCO 0.00523 mol/min CO 15.5 g/kg fuel Fuel 389 g/kW-hr Consumption NO 391ppm CO₂ 0.68 mol/min CO₂ 3189 g/kg fuel Particulate 7.97 g/kg fuel NO₂19.9 ppm NO 0.0113 mol/min NO 35.9 g/kg fuel Particulate 3.10 g/kW-hrspeed 1393 rpm NO₂ 0.000574 mol/min NO₂ 2.80 g/kg fuel load 7.34 ft-lbTheoretical CO₂ 23672 → % Difference 109 particulate mass 4.81 mg ModeIII MAF (freq) 3522 Hz Air Fuel Ratio 57.5 HC 0.0815 g/min Brake Power3.79 kW Mass Air Flow 1136 g/min Exhaust Density 0.678 kg/m3 CO 0.222g/min HC 1.29 g/kW-hr Fuel Consumption 19.7 g/min Mass Exhaust 1156g/min CO₂ 64 g/min CO 3.51 g/kW-hr Exhaust Temp. 258° C. Volume Exhaust1.70 m3/min NO 0.521 g/min CO₂ 1008 g/kW-hr HC 142 ppm Moles in Exhaust39.1 mol/min NO₂ 0.0555 g/min NO 8.24 g/kW-hr CO 202 ppm HC 0.00555mol/min HC 4.13 g/kg fuel NO₂ 0.88 g/kW-hr CO₂ 79181 ppm CO 0.00792mol/min CO 11.2 g/kg fuel Fuel 312 g/kW-hr Consumption NO 444 ppm CO₂1.45 mol/min CO₂ 3228 g/kg fuel Particulate 6.53 g/kg fuel NO₂ 30.9 ppmNO 0.0174 mol/min NO 26.4 g/kg fuel Particulate 2.04 g/kW-hr speed 1761rpm NO₂ 0.00121 mol/min NO₂ 2.81 g/kg fuel load 15.2 ft-lb TheoreticalCO₂ 37022 → % Difference 113.9 particulate mass 8.08 mg Mode II MAF(freq) 3703 Hz Air Fuel Ratio 43.9 HC 0.0618 g/min Brake Power 6.42 kWMass Air Flow 1313 g/min Exhaust Density 0.568 kg/m3 CO 0.221 g/min HC0.578 g/kW-hr Fuel Consumption 29.9 g/min Mass Exhaust 1343 g/min CO₂ 98g/min CO 2.06 g/kW-hr Exhaust Temp. 361° C. Volume Exhaust 2.366 m3/minNO 0.768 g/min CO₂ 913 g/kW-hr HC 92.7 ppm Moles in Exhaust 45.5 mol/minNO₂ 0.0485 g/min NO 7.18 g/kW-hr CO 173 ppm HC 0.00421 mol/min HC 2.07g/kg fuel NO₂ 0.453 g/kW-hr CO₂ 117828 ppm CO 0.00788 mol/min CO 7.38g/kg fuel Fuel 280 g/kW-hr Consumption NO 563 ppm CO₂ 2.219 mol/min CO₂3263 g/kg fuel Particulate 2.75 g/kg fuel NO₂ 23.2 ppm NO 0.02560mol/min NO 25.7 g/kg fuel Particulate 0.770 g/kW-hr speed 1995 rpm NO₂0.001054 mol/min NO₂ 1.62 g/kg fuel load 22.7 ft-lb Theoretical CO₂48801 → % Difference 141 particulate mass 3.34 mg Mode I MAF (freq) 3827Hz Air Fuel Ratio 33.9 HC 0.0707 g/min Brake Power 8.88 kW Mass Air Flow1441 g/min Exhaust Density 0.470 kg/m3 CO 0.291 g/min HC 0.478 g/kW-hrFuel Consumption 42.5 g/min Mass Exhaust 1483 g/min CO₂ 140 g/min CO1.97 g/kW-hr Exhaust Temp. 494° C. Volume Exhaust 3.16 m3/min NO 0.927g/min CO₂ 949 g/kW-hr HC 96.0 ppm Moles in Exhaust 50.2 mol/min NO₂0.0156 g/min NO 6.26 g/kW-hr CO 207 ppm HC 0.00482 mol/min HC 1.66 g/kgfuel NO₂ 0.11 gmkW- hr CO₂ 167474 ppm CO 0.01041 mol/min CO 6.86 g/kgfuel Fuel 287 g/kW-hr Consumption NO 615 ppm CO₂ 3.19 mol/min CO₂ 3307g/kg fuel Particulate 4.12 g/kg fuel NO₂ 6.8 ppm NO 0.0309 mol/min NO21.8 g/kg fuel Particulate 1.18 g/kW-hr speed 2197 rpm NO₂ 0.000339mol/min NO₂ 0.37 g/kg fuel load 28.5 ft-lb Theoretical CO₂ 63592 → %Difference 163 particulate mass 6.44 mg ISO 8178 Weighted Average TotalsHC 0.855357 g/kWh CO 2.855434 g/kWh CO₂ 983.3241 g/kWh NO 8.17224 g/kWhNO₂ 0.543094 g/kWh Particulate 1.392242 g/kWh % Coated BaselineReduction HC 0.855357 1.101877 22.4% CO 2.858434 3.66792 22.1% CO₂983.3241 908.0019 −8.3% NO 8.17224 5.867477 −39.3% NO₂ 0.543094 0.85306636.3% Particulate 1.392242 1.937068 28.1%

The raw data associated with the various runs used to arrive at theabove reductions is provided in Tables 5 and 6. Table 5 represents dataassociated with the baseline engine. Table 6 represents data associatedwith the use of the coated cylinder head. Four test sets were conductedfor both baseline and coated conditions, with the engine rpm being setin accordance with ISO 8174 Part 4.

The above data illustrate the potential for reduction of particulatematter (hereafter “PM”) constituents in the exhaust stream. Also,unburned hydrocarbons and carbon monoxide emissions are reduced. Theamount of the carbon dioxide constituent showed an increase, indicativeof a more complete combustion of the hydrocarbon based fuel.

Using the characteristics of the Yanmar engine, as shown in FIG. 3,allows examination of the effect of coating various surfaces on the SACto SA_(p) ratio. The engine has a estimated piston surface area of8011.6 mm². The piston (not shown) has an estimated diameter of 101 mm,as compared to the bore diameter of 102 mm. The pocket 302 formed in thehead 304 is fairly flat, with the area surrounding the direct injectionport 306 being pocketed. The surface area of the pocket is approximately5890 mm². The surface area of a top ring (not shown) would beapproximately 91 mm². If the rings were the only coated component, theSAC to SA_(p) ration would be approximately 1.135. By coating only thetop surface of the piston, an SAC to SA_(p) ratio of 1 can be achieved.Coating the top surface of the piston and the pocket of the head (butnot the valve faces) would yield an SAC to SA_(p) ratio of approximately1.73. Coating the pocket 302 of the head 304 and the intake valve face308 and the exhaust valve face 310 would yield an approximate SAC to SApratio of 1.023.

Application Process

The coatings of the present invention may be applied to the combustionsurfaces using a high-velocity-oxygen-flame process. Other suitableknown application processes may also be used. It is believed thatutilization of direct current (DC) heating of an engine component beingcoated promotes the bonding between the component and the coating. It isalso believed that the use of the DC current generates an associatedinduced magnetic effect, further promoting the bonding between thecoating and a component being coated. Alternately, the coating may beapplied using a plasma process. The plasma process may not, however,create the same strength of bond between the coating and the component.

Reconditioned Head Market

One significant advantage of the present coating technology is theability of the coating to be a component involved in the enginereconditioning process. Material frequently is removed from combustionchamber surfaces during operation or restoration. Particularly,machining may be required in order to correct surface tolerances wherematerial removal has been such that components can no longer meetspecifications. Previously, the components would be discarded sincetolerances could not be met. Application of the present coating allowsmaterial to be added, potentially allowing previously un-useablecomponents to be returned to service. The addition of the material maycover surfaces which are typically machined during a rebuilding process.The coating of the present invention does not necessarily prevent suchmachining. Accordingly, valve seats and the mounting surface between thehead 304 and the block (not shown) may be accomplished using standardmethods.

Additional Effects

As is apparent from the test data, one artifact of the use of thepresent coating is an increased exhaust temperature. This effect isbelieved to be associated with the additional chemical reduction ofhydrocarbon molecules. The temperature of the exhaust stream may affectthe performance of downstream catalysts. The elevated temperaturesassociated with the present invention may allow the downstream catalyticmaterial to have a greater chemical effect, as well as assist thecatalytic material in regenerating. Accordingly, the efficiency ofdown-stream catalysts may be improved due to the higher exhausttemperatures associated with the present coating.

The energy of the exhaust stream has been used to drive turbochargers,which use the exhaust stream energy to drive a compressor thatcompresses the fuel-air charge before it enters the combustion chamber.The efficiency of a turbocharger is dependant on the different betweenthe upstream and downstream pressures and temperatures. Higherefficiency in the conversion of energy contained within the exhauststream into mechanical energy therefore may accrue in conjunction withthe use of the present coatings, as the higher exhaust streamtemperature may result in higher gas volume for a given air-fuel charge.

Application to Internal Combustion Engines Using Fuels Other than DieselFuel

Although the presently preferred embodiment of the invention envisionsapplication of the coating of the present invention to combustionsurfaces of a diesel fueled engine, the coating may be applied to otherengines using fuels which rely on the oxidation of hydrocarbon moleculesas an energy source. Such fuels may include petroleum based fuels,alcohol based fuels, gaseous fuels such as natural gas or propane, orfuels synthesized from other sources. The catalytic effect of the nickelsurface on hydrocarbon fuels using lighter fractions may be lesspronounced than with the diesel fuels, however the benefit ofapplication of the coating of the present invention may be warranted aslower emission requirements and higher fuel prices affect theoperational constraints of internal combustion engines.

One particular application to which the present invention is believedamenable are engines using dimethyl ether (CH₃OCH₃), either in straightdiesel cycle, spark assisted ignition, or spark ignited engines.Dimethyl ether is believed to be an alternate fuel for commercial dieselengines. The use of dimethyl ether in diesel cycle engines has yieldedreduced NOx emissions, however HC and CO emissions are increased. It isbelieved that the use of a nickel coating applied to the combustionchamber of an internal combustion engine using dimethyl ether wouldtherefore exhibit reduced NOx, CO and HC emissions due to the inherentqualities of the dimethyl ether in conjunction with the catalyticreaction associated with the nickel coating.

The present invention may be embodied in other specific forms than theembodiments described above without departing from the spirit oressential attributes of the invention. Accordingly, reference should bemade to the appended claims, rather than the foregoing specification, asindicating the scope of the invention.

1) An internal combustion engine having at least one reciprocatingcomponent, a bore within which the at least one reciprocating componentreciprocates, and a closure over one end of the bore associated with theat least one reciprocating component, said reciprocating componenthaving at least one combustion face, said combustion face defining acombustion face area, said reciprocating component further reciprocatingrelative to the closure and having a position at which the combustionface is at a closest point to the closure, wherein a combustion volumewithin which an air/fuel mixture is combusted is defined at least inpart by the combustion face of the reciprocating component, and asurface of the closure, wherein at least a portion of the surfaces whichdefine the combustion volume are coated with a substantially homogenousmetallic coating comprising between greater than 15% and about 80%nickel such that when the combustion face is at the position at whichthe combustion face is at a closest point to the closure, the coatingcovers an area of the combustion surfaces at least as large asapproximately 10% of the area of the combustion face, and furtherwherein said coating is exposed to combustion gases. 2) An internalcombustion engine having at least one reciprocating component, a borewithin which the at least one reciprocating component reciprocates, anda closure over one end of the bore associated with the at least onereciprocating component, said reciprocating component having at leastone combustion face, said combustion face defining a combustion facearea, said reciprocating component further reciprocating relative to theclosure and having a position at which-the combustion face is at aclosest point to the closure, wherein a combustion volume within whichan air/fuel mixture is combusted is defined at least in part by thecombustion face of the reciprocating component, and a surface of theclosure, wherein at least a portion of the surfaces which define thecombustion volume are coated with a substantially homogenous metalliccoating comprising between about 10% and about 40% chromium such thatwhen the combustion face is at the position at which the combustion faceis at a closest point to the closure, the coating covers an area of thecombustion surfaces at least as large as approximately 10% of the areaof the combustion face, and further wherein said coating is exposed tocombustion gases. 3) A method for fabricating a reduced emissions dieselengine component, wherein said component forms a combustion surface fora diesel engine and wherein a portion of said component which forms acombustion surface has inadequate material to meet design geometry,comprising the steps of coating at least the portion of said componentwhich forms a combustion surface with a substantially homogenous coatinghaving at least sufficient thickness to allow said surface to meetdesign geometry, wherein said coating comprises nickel, chromium, andiron; and machining a portion of the coating from the surface to restoredesired tolerances.